OMIA 000438-9796 : Haemophilia B in Equus caballus

In other species: domestic cat , dog , pig

Possibly relevant human trait(s) and/or gene(s)s (MIM numbers): 306900 (trait) , 300746 (gene)

Mendelian trait/disorder: unknown

Considered a defect: yes

Cross-species summary: Also called factor IX deficiency or Christmas disease. This is one of the two X-linked bleeding disorders, haemophilia A being the other. The fact that these two disorders are X-linked in all species reported to date provides strong support for Ohno's suggestion that the X chromosome has been highly conserved throughout evolution.


1956 Sjolin, K.E. :
Lack of Christmas factor in horse plasma. Nature 178:153, 1956. Pubmed reference: 13348654.

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  • Created by Frank Nicholas on 19 Jan 2016